1. Avoid using contractions in formal writing. A contraction is a combination of two words as one, such as "don't," "can't," and "isn't." The use of contractions is inappropriate in formal legal writing. Replace them with the two-word version of the contraction. (来源：英语学习门户网站EnglishCN.com)
在正式写作中应避免使用缩写形式。 缩写即是将两个词合二为一，比如 "don't," "can't," 和"isn't"。在正式的法律文书中使用缩写形式是不规范的。 (来源：EnglishCN英语问答中心[e问e答])
Incorrect: He can't guarantee that the defendant will appear because the defendant hasn't called him in several days.
Correct: He can not guarantee that the defendant will appear because the defendant has not called him in several days. (来源：英语论坛 http://bbs.englishcn.com)
2. Remember: "It's" is the contraction of "it is." The term "its" is the singular possessive of "it." The term "it's," by contrast, is the contraction of "it is."
Correct use as Possessive: 所有格的正确使用：
My '68 Mustang is on its last journey.
Correct use as Contraction: 缩写形式的正确使用：
It's a long way from Tipperary. (来源：英语麦当劳－英语快餐EnglishCN.com)
Cross References: Apostrophes, Possessives 参考：省略符号，所有格